Evaluation of the Peripheral Smear Flashcards
Value of Peripheral Blood Smear Review
Inexpensive but a powerful diagnostic tool.
Provides information regarding bone marrow function and disorders.
Assists in assessment of anemias, white and red cell disorders, and thrombocytopenias.
How to Prepare a Peripheral Smear
“Wedge Technique”
Blood will go from thick to thin. View where the cells are a single layer and have a little “daylight”.
Red Cells
Size-
6-8μm diameter; 2-2μm thick
Shape-
Biconcave discs
Normal number-
4-6 x 106/μL
Color-
Area of central pallor surrounded by hemoglobin
Anisocytosis
Definition Anisocytosis: Considerable variation in the size of cells that are normally uniform, especially such a variation in red blood cells.
Some Causes of Anisocytosis
Fe deficiency Sideroblastic anemia Vitamin A deficiency Myelodysplastic syndrome Hemoglobin H disease Kwashiokor Folate deficiency Vitamin B12 deficiency Blood transfusion Beta thalassaemia
Microcytosis
Iron deficiency anemia Thalassemia Anemia of chronic disease Sideroblastic anemias Chronic lead exposure
Macrocytosis
Folate/B12 deficiency
Liver disease/ETOH
Primary bone marrow failure; myelodysplasia
Reticulocytosis (polychromasia)
Poikilocytosis
Variations in Red Cell Shape
Macroovalocytes
B12/folate deficiency (megaloblastic anemia)
Elliptocytes
hereditary
Fragmented erythrocytes (schistocytes)
TTP (Thrombotic thrombocytopenic purpura)
DIC (Disseminated intravascular coagulation )
HUS (Hemolytic uremic syndrome )
Defective heart valves
Hemolytic anemias
Acanthocyte
(Burr Cell) Red cells with irregularly spaced projections, variable in width with rounded ends. Seen in liver disorders.
Codocyte
(Target Cell) Red cells with central color spot in area of pallor; seen in Sickle cell, HbC & the thalassemias.
Dacrocyte
Teardrop shaped red cells Seen in myeloproliferative disorders, myelofibrosis, pernicious anemia and thalassemias.
Stomatocyte
Folded RBC mimicking a mouth and lips (slit-like appearance). Seen in hemolytic anemias, either constitutive or acquired
Sickle Cell Anemia
Marked Poikilocytosis and Anisocytosis
Sickle Cell Disease:
Two Classic Poikilocytes
Sickle cells
Target cells
Hemoglobinopathies
Sickledex Solubility Test for
SS trait and disease.
Beta-thalassemia blood smear
Marked poikilocytosis - abnormal shaped RBC’s) plus anisocytosis
with numerous microcytes.
Normochromic and Hypochromic”
Chromic: Greek chroma - color “Hypochromia”: reduction in color intensity for an object from its normal state
Hypochromia on peripheral smear indicates increased central pallor of RBCs
Normochromic: RBCs contain normal hemoglobin concentration & stain with normal red intensity on peripheral smear with a Romanowsky stain
Hypochromic indicates the red cells contain a decreased concentration of hemoglobin. Red cells exhibit an increased area of central pallor.
No “Hyperchromia”. Can only cram 270 million hemoglobin molecules into red cell.
Variations in Red Cell Color (Chromia)
Central pallor should be approximately 1/3 of the cell
Increased central pallor (hypochromic)
- Thalassemia
- Iron deficiency anemia
- Sideroblastic anemia
Decreased central pallor
- Hereditary spherocytosis
- Autoimmune hemolytic
anemia
Hypochromic Microcytic
Hypochromic microcytic anemia of iron deficiency. Note small red cells containing a narrow rim of peripheral hemoglobin. Scattered fully hemoglobinized cells are present due to recent blood transfusion and stand in contrast to the “empty” hypochromic microcytic red cells.
Rouleaux
“stack of coins”
Multiple myeloma
Due to elevated plasma
fibrinogen or globulins
Clumping
Cold agglutinins
Immature Red Cells (Nucleated Red Cells, Normoblasts)
Nucleated red cells (normoblasts): immature red cell progenitors not normally present in blood. Normoblast size is 7 to 12 µm in diameter with a pink cytoplasm (Hgb). The nucleus is pyknotic (a homogeneous blue-black mass with no structure).
Indicators of Increased Hematopoiesis/Stressed Bone Marrow
Increased hematopoiesis:
Reticulocytes
Nucleated RBCs
(Normoblasts)
Inclusions
Basophilic stippling: round, dark-blue granules in reticulocytes on smears stained with supra vital stains (brilliant cresyl blue).
The granules are precipitated ribosomes and mitochondria. Classic finding in lead poisoning.
Howell-Jolly bodies: Spherical blue-black red cell inclusions seen on Wright-stained smears.
They are nuclear fragments of condensed DNA, 1-2 µm diameter, normally removed by the spleen. Seen in severe hemolytic anemias and in post-splenectomy patients (below).
White Cells
Part of a complete blood count (CBC) is a differential
- It “differentiates” the 5 main types of WBCs by assigning a percentage of each type after counting 100 WBCs on the peripheral smear
- There is a reference range (% of total WBC) for each type
-
** Absolute (Neutrophil)count = % x Total WBC
Neutrophils
50-60% Elevated in bacterial infections, stress, corticosteroid therapy Immature forms often present with elevated count
Lymphocytes
30-40% of circulating WBCs
Elevated in viral infections (Epstein-Barr, etc.)
“atypical” lymphocytes (mono)
Fragile lymphocytes (smudge or basket cells) are common in chronic lymphocytic leukemia (CLL)
Large nucleus to cytoplasm
Eosinophils
< 5%
Elevated in parasitic infections,
allergies
Basophils
< 1%
Elevated in chronic
myelogenous leukemia (CML)
Large granules
Left shift
increase in immature forms in peripheral blood due to increased production:
Infections, myeloid cancers
Dohle bodies:
Seen in systemic infectious or inflammatory disease
Often accompanied by a left shift, toxic granulation and cytoplasmic vacuoles
Hypersegmented Neutrophils
> 5 lobes
Can be seen in megaloblastic anemias
B12 and folate deficiency
Reduced lobulation of mature neutrophils
Pelger-Huet anomaly
Often associated with myelodysplastic syndromes
Other Abnormal WBC Findings: Blasts
may indicate WBC neoplasia (myeloid or lymphoid leukemias)
Other Abnormal WBC Findings: Plasma cells-
may indicate lymphoid neoplasia (e.g., multiple myeloma)
Normal platelet count:
150,000-450,000/μL
under 25,000 – spontaneous bleeding
>1,000,000 – spontaneous clotting
1 unit of platelets = increase of 5,000. Never give 1 unit, 5 or more.
Giant platelets
Suggest marrow response secondary to increased platelet destruction or consumption
- Congenital disorders
- Immune destruction
- Disseminated intravascular coagulation (DIC)
- Hemolytic uremic syndrome (HUS)
- Thrombotic thrombocytopenic purpura (TTP)
Clinical manifestations of thrombocytopenia or dysfunctional platelets-
Petechiae
Purpura
Lymphadenopathy
Lymphadenopathy: Painless enlargement of a lymph node or group of nodes
Applies to any enlargement of lymph node(s)
Infection most likely cause of lymphadenopathy, particularly in children
- Viral infection most likely cause of lymphadenopathy
Supraclavicular and axillary lymph node enlargement is more concerning
Lymph node > 4 centimeters most likely is malignant
Lymphadenitis
Acute Nonspecific Lymphadenitis: Swollen, edematous tender** (painful) with distended capsule
Chronic Nonspecific Lymphadenitis
Enlarged but painless; capsule is proportionally enlarged. Nodes are palpable (> 2cm).
Chronic Nonspecific Lymphadenitis Exhibits three patterns
Stimulate B-cell populations: Follicular Hyperplasia (rheumatoid arthritis, toxoplasmosis, early stages HIV)
Stimulate T-cell populations: Paracortical Hyperplasia (infectious mono, acute viral infections, following vaccinations, reactions to Dilantin.)
Stimulate macrophages: Sinus Histiocytosis (e.g. in axillary nodes draining a region of breast cancer.)
Reactive Hyperplasia
Manifestations of immune response
B cell transformation/proliferation –
Follicular hyperplasia of CD 20+ B-cells in follicles (3)
T cell transformation/proliferation –
Diffuse interfollicular hyperplasia of CD3+ T-cells in paracortex (6)
Histiocyte recruitment/activation –
Subcapsular and paracortical sinus histiocytosis (2&6)
Cat Scratch Disease
- *Initially, sarcoid-like granulomas
- *Later stellate necrotizing granulomas
(Self-limited lymphadenitis usually of head and neck
Bartonella henselae
Cat scratch, splinter or thorn
Primarily in children
Rarely encephalitis, osteomyelitis, or thrombocytopenia)
